Birdsong
Architect - ALA Architecture
Formwork system - Supreme 150
Core size - 159mm/6"
Shortlisted for Best Eco Home at the 2026 Build It Awards!
This modest three-bedroom family home, designed by ALA Architecture, is a benchmark in sustainable residential design. Built to Passivhaus principles and the first home in the UK to receive the AECB CarbonLite certification plaque, it exemplifies how intelligent design and advanced building systems can deliver outstanding comfort and efficiency within a modest footprint.
Constructed using the R-Wall system, including the Underslab insulation system and Supreme 150 board achieving a U-value of 0.11, the home offers exceptional thermal performance and airtightness. Despite being a first-time R-Wall user, the architect successfully completed the build as a self-build project, demonstrating the system’s accessibility and efficiency for both professionals and individual builders.
The results speak for themselves — in its first year of occupancy (August 2024 – July 2025), the property’s total electricity bill, including standing charges, heating and cooling, hot water, lighting, cooking, working from home, charging two electric vehicles, and regular use of power tools, came to –£25, reflecting the home’s remarkable energy-positive performance.
This project stands as a testament to what’s achievable when innovative design, sustainable technology, and high-performance materials like R-Wall come together to redefine modern, low-energy living.
£25,333
Total Formwork square meterage cost
(Completed formwork inclusive of lintels and cavity closers. Not including concrete, price shown is before VAT)
0.11
Achievable U-Value
14
Superstructure completion time
(Days)
Project Gallery
